Late on the night of Friday, July 18, 1969, Sen. Ted Kennedy left a party he was hosting on Chappaquiddick Island, off the coast of Massachusetts, and promptly drove his car off a one-lane bridge into a tidal channel. He escaped without serious harm, but his sole passenger — 28-year-old campaign worker Mary Jo Kopechne — was not so fortunate; she drowned during the accident. What really took place on that fateful evening, including why Kennedy waited 10 hours before reporting the incident to authorities, remains a confounding American mystery, and one that likely compelled Kennedy to avoid running for president after the assassination of his brothers John and Bobby. But a new film will look to answer questions about the scandalous incident when it arrives in theaters in April — and we have its exclusive first trailer.

Chappaquiddick, which premiered at last year’s Toronto International Film Festival, stars Jason Clarke as Kennedy and Kate Mara as Kopechne, alongside a sterling cast that also includes Ed Helms (as Kennedy cousin Joe Gargan), Bruce Dern (as Joseph P. Kennedy Sr.), Jim Gaffigan (as Gargan’s pal Paul F. Markham), Taylor Nichols (as lawyer Ted Sorensen), and Clancy Brown (as Robert McNamara). As the above clip lays out, it will be a drama that strives to get to the bottom of what really happened in Kennedy’s car before, during, and after it plunged into the water, and to investigate the ramifications for Kennedy’s career — and, in turn, for American politics. Certainly, it will be aided by the fact that Clarke, though not much of a visual dead ringer for Kennedy, sounds just like him and carries himself with a physical weight that speaks to the man’s multifaceted feelings about the tragedy.

While reviews out of Toronto were mixed, Chappaquiddick’s real-life political cover-up story will no doubt resonate with many, given the current raft of White House scandals.